Viscosity of CaO–SiO2–Al2O3–MgO–TiO2–FeO Slag in HIsmelt Process: Influence of TiO2 Content on Viscosity and Crystallization

Vanadium–titanium magnetite is a complex ore with iron, vanadium, titanium, and other valuable elements, and it is of great significance to recycle the valuable elements. HIsmelt smelting reduction of vanadium–titanium magnetite is a clean and effective ironmaking process. The effect of TiO2 content on the viscosity of CaO–SiO2–Al2O3–MgO–TiO2–FeO slag system is studied by rotating cylinder method. The composition and microstructure of crystalline phase are analyzed by XRD and SEM–EDS, and compared with the thermodynamic calculation results of FactSage8.1. The results show that the viscosity of molten slag decreased with the increase of TiO2 content, and TiO2 content has a great impact on the viscosity, when the TiO2 content in the slag is less than 20 pct and the temperature is less than 1395 °C. With the increase of TiO2 content, the diffraction peak of perovskite is enhanced, the gehlenite and akermanite are gradually reduced, the shape of perovskite changes from irregular polygon to needle dendrite, and the number also increases gradually. When the TiO2 content reaches 20 pct, the perovskite reaches saturation state. With the increase of TiO2 content, the main precipitates change from perovskite, gehlenite, and akermanite to perovskite, anorthite, and titania spinel. Titanium existed in the slag as perovskite first, and then as baikovite and titanium spinel. Therefore, for high-titanium slag, the TiO2 content has little effect on the fluidity of HIsmelt process slag.